BURLINGTON COUNTY, N.J. - In South Jersey, the discovery of unexploded artillery shells from World War II has stalled plans to develop a new expo center. The sheer number of artillery shells staggered the mayor.

It was found at the now closed Palmyra Drive-In Theater on Route 73.

People who work next to the old theater said they've been hearing authorities detonate old Army munitions on Thursdays.

The old munitions were found on the site that the borough wants to develop.

"We were hoping, hoping to only find one or two or three maybe. We're now up to nearly 200, or 181 as reported to the New Jersey Department of Environmental Protection, but there's since been another 20," Palmyra Mayor John Gural, Jr. said.

The Army was anxious to develop new anti-tank rounds for the military during World War II. So the secret test site was what later became the Palmyra Drive-In Theater.

The artillery shells were developed over at the Frankford Arsenal. And while some were tested on the site of what was to be the drive-in, other shells got there the old fashion way -- the Army actually fired them from Philadelphia, across the river, into Palmyra.

When the war ended, the Army said the site was cleaned up. The land returned to civilian use, which in this case became a drive-in, complete with concession stands.

"It's scary. We've literally been living in a minefield out there for all of these years," Gural said. "All of the shells are, have live fuses. Some of them contain high explosive materials."

Thousand upon thousands of men, women, and children used those concession stands over the years. And probably few of them ever knew what was really buried beneath the land.

John Kozierachi owns a business right next to the old drive-in and remembers being there in the good old days.

"I did when I was a kid, yes I did. Obviously, you wouldn't go back," Kozierachi, of Pennsauken, said.

"How long have they been there?" Marie Furey, of Cinnaminson, said. "So, that should have been closed a long time ago."

When the drive-in closed, the site was used for a flea market. Police ordered it shut down in March because some of the shells were sticking out of the ground.

Until the shells are removed, the development of a 200,000-square-foot expo center -- a revenue maker for Palmyra -- is on hold.